1. Field of Invention
The present invention pertains to the art of washing machines, and more particularly, to a control system for braking an inner tub of a washing machine through a critical speed range within which an out-of-balance condition could occur, such that the washing machine is not exposed to high vibration levels.
2. Discussion of Prior Art
Typical washing machines perform a wash cycle by agitating or tumbling a load of clothes bathed in a water or water/detergent solution within an inner tub. After the wash cycle has completed, a spin cycle, including an extraction phase and a deceleration phase, is required. Most machines perform this cycle by spinning the inner tub at a high rate such that centrifugal forces cause the water or water/detergent solution to separate from the clothes. After a predetermined period has elapsed, drive to the inner tub is disrupted whereby the inner tub is slowly brought to a stop.
It is well known in the art that, prior to the extraction or dehydration phase, the clothes can become unevenly distributed within the inner tub. During the extraction phase of the spin cycle, the uneven distribution of the clothes results in an out-of-balance condition which causes excessive vibration of the machine. For this reason, it is known to incorporate out-of-balance sensors in washing machines to determine the presence of such a condition which can be counteracted such that the effects caused by the vibrations are reduced. While these corrective measures are effective, they focus on the extraction phase of the spin cycle, as opposed to the deceleration phase of the cycle. However, during the deceleration phase, an out-of-balance condition can cause the machine to experience similar vibration problems as during the extraction phase of the spin cycle. Accordingly, based on at least these reasons, there exists a need in the art for a braking system which will effectively and efficiently reduce the effects of vibration on a washing machine, thereby enhancing the effective life of the machine and protecting its various components.